Refactored ShouldVerb, CanVerb, and MustVerb so they are traits with
an abstract left val. Then had to also tweak stack depths for registered
scopes in the Locations. And made StringShouldWrapper now extend the
trait instead of a class, and made its left param a parametric field.
Made StringShouldWrapper extend AnyRefShouldWrapper.
Have ResultOfCollectedString extend ResultOfCollectedAnyRef.
Made NumericShouldWrapper extend AnyShouldWrapper.
Got rid of NumericShouldWrapper in its entirety by moving numeric-related methods to
AnyShouldWrapper and using implicit parameters to limit their scope to just numerics.
Manged to drop six implicit conversions this way.
Deleted commented out NumericShouldWrapper code, and then fixed a few
failed tests found after doing a clean build.
Make ArrayShouldWrapper extend AnyRefShouldWrapper
Deleted commented out code.
Added missing copyright notices.
Added DocSpec files to 2.9_excludes.